Clip for sanding tool or the like



oct. 31, 1967 A, A@ HUT-@HWS 3,349,523

CLIP FOR SANDING TOOL 0R THE LIKE Filed May 1'?. 1965 ArtoNEv Patented Get. 3l, 1967 3,349,523 CLIP FR SANDING TOOL R THE LIKE Alma A. Hutchins, 3190 Primavera St., Pasadena, Calif. 91107 Filed May 17, 1965, Ser. No. 456,383 24 Claims. (Cl. 51-386) ABSTRACT 0F THE DISCLGSURE A clip for retaining a sheet of sandpaper or the like on an abrading tool and preferably including a tubular rotary element having a slit in its side wall through which an end portion of the sandpaper extends, with the sandpaper passing between the tubular member and an opposed surface, and with the tubular member being urged rotatably in a takeup direction by a spring having a torsion portion extending axially within the tubular member, and having an actuating arm at an end of the tubular member.

This invention relates to improved abrading tools, adapted to carry a sheet of abrasive material, such as sand paper, which is to engage and act on a work piece. The invention is especially concerned with an improved clip structure for releasably attaching an abrasive sheet to the body of such a tool.

In prior sanding devices, particularly those of the power operated type, great ydifliculty has been encountered in effectively securing a strip of sand paper or other abrasive material to the vibrating or oscillating shoe of such a device, in a manner assuring positive retention of the abrasive sheet in operation. As will be understood, the constant vibration, reciprocation, or rotary oscillatory movement of thesanding portion of such a tool tends continually to displace the abrasive sheet relative to the part by which it is carried, and therefore tends to pull the ends of the abrasive sheet away from whatever clips may have been employed for retaining that sheet in place. This diiculty has been so bothersome in the past that, in spite of the fact that many different types of clips have been designed for the purpose of retaining an abrasive sheet on a tool, none of these prior clips with which I am familiar has proven wholly satisfactory for power operated sanding devices. As a result, it is currently the practice to not rely on clips in such sanding tools, but instead to utilize a cement for directly adhering the abrasive sheet, across its entire surface, to the tool shoe by which it is carried. Such cementing of each sheet utilized to the tool is obviously a very inconvenient and time consuming process which detracts considerably from the advantages to be attained by use of the tool.

A major object of the present invention is to provide an improved clip structure which is capable of retaining an abrasive sheet on a tool much more effectively than prior clip arrangements, and in fact with such a positive type of action as to completely prevent any accidental dislocation of the sheet from the tool, and thereby preclude the necessity for cementing the sheet in place. This clip is especially intended for use on power actuated Sanders, but of course may also be employed to advantage on manually operated abrasive holders which have no driving motor.

A clip constructed in accordance with the invention is adapted to be actuated between an abrasive holding position and a released position for removal of the abrasive sheet with great simplicity, and preferably by a single swinging motion of an actuating part. An important ad- -vantage of the present clip resides in the fact that it is capable in its active working position of continually exerting a yielding force on the gripped paper or abrasive sheet, acting to automatically take up any looseness which may develop in the sheet, and permanently maintain it in tightly stretched condition on the tool. At the same time, these results are all achieved in an arrangement having great structural simplicity, and in which all of the parts are suiciently rugged and strong as to virtually eliminate any possibility of malfunctioning or breakage of any part of the clip, and therefore render the clip permanently reliable in operation over the entire life of the tool.

Structurally, a clip embodying the invention desirably includes a holding element which is adapted to grip a portion of the abrasive sheet, and which is mounted to turn about a predetermined axis in a manner exerting a pull on the sheet. In conjunction with this holding unit, I utilize means for yieldingly exerting a rotative force on the holding element, urging it rotatively in the takeup direction to tighten the sheet. Preferably, the holding unit takes the form of a tubular element having a side wall with a slit down one of its sides into which an end of the abrasive sheet is projectable. The yielding means for exerting take-up force on the holding unit may include a unique spring structure, preferably having a portion disposed Within the holding unit, and preferably also having a swinging actuating arm by which the spring force is applied to the holding unit. The portion of the spring unit which is located within the holding unit may -be a torsion rod, while the swinging arm may also be a spring having resilience for applying the desired yielding force. Preferably, the arm and the torsion element are formed as portions of a single elongated spring element bent to proper shape. The spring may be retained in active gripping position by engagement with a suitable locking structure, preferably by simple holding engagement with a ange formed on the body element Iwhich carries the abrasive material.

The holding unit may be received closely adjacent an opposed surface of the carrying body, in a manner such that the abrasive sheet is received between that surface and the holding unit, with the latter desirably being spring urged toward the mentioned surface. For this purpose, a leaf spring may act to urge the holding unit against the opposed surface, and may also function as a locating structure for confining the holding unit in a manner such that its only freedom for motion is the discussed rotary motion about its longitudinal axis.

The above and other features and objects of the invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawing, in which:

FIG. 1 is a side view showing a power actuated sanding tool constructed in accordance with the invention;

FIG. 2 is a greatly enlarged fragmentary side view showing one of the end clips of the FIG. 1 tool;

FIG. 3 is a fragmentary vertical section taken on line 3 3 of FIG. 2;

FIG. 4 is a fragmentary plan view taken on line 4-4 of FIG. 2;

FIG. 5 is a view similar to FIG. 2, but showing the clip in its released position; and

FIG. 6 is a horizontal section taken on line 6 6 of FIG. 5.

Referring first to FIG. l, I have shown at 16 a power operated sanding tool having a main body section 11 and a shoe section 12 which is mounted to oscillate relative to section 11. The shoe 12 carries at its underside an elongated strip 13 of abrasive sheet material, typically sandpaper, which is retained on the shoe by a pair of end clips 14 with which the present invention is especially concerned.

The main body section 11 may take any of numerous different shapes, but is typically illustrated somewhat diagrammatically as including a horizontally extending plate like element 15, having a rotary motor 16 mounted to its upper side, which motor may be energized electrically or by compressed air fed to the motor through an inlet hose 17. Section 11 may be grasped and manipulated by two handles represented at 18 and 19.

The shoe 12 includes a rigid shoe body member 20 taking the form essentially of a horizontal plate formed of sheet aluminum or other essentially rigid metal. This body or plate 20 extends parallel to member 15 of section 11, and is mounted to member 15 for horizontal oscillatory movement by four vertically extending flexible rubber connector members 21, whose upper ends are suitably fastened to member 15, and whose lower ends are similarly fastened to plate or body 20. Motor 16 has a shaft 22, which rotates about a vertical axis 23, and which has an eccentric portion 24 journalled within a ball bearing 25 connected in fixed position to the upper side of plate 20, so that powered rotation of shaft 22 causes rotary oscillation of the entire bearing 25 and the connected plate 20 and its carrier abrasive material 13.

As seen best in FIGS. 2, 3 and 4, sheet metal plate 20 of the shoe preferably has two parallel vertically extending flanges 26 formed integrally with the main horizontal portion 27 of plate 20, and projecting upwardly along its opposite sides in two vertical planes 28 (FIG. 4) which extend parallel to the main central longitudinal axis 29 of the tool and its plate 20. At the opposite ends of plate 20, these anges 26 may have their upper edges inclined downwardly at 30 (FIGS. l, 2 and 5). At the underside of the horizontal portion 27 of plate 20, there is carried a rectangular cushion 31 (FIG. 2), which may be formed of rubber, and may be horizontally coextensive with plate 20. The sheet of sandpaper 13 is of a width 32 (FIG. 4) corresponding approximately to the width of plate 20 and cushion 31, and is of a length (parallel to axis 29) sutiiciently greater than plate 20 to enable the sandpaper to be turned upwardly about the ends of plate 20 and cushion 31 (FIG. 2), and to be properly gripped by clips 14. The width 32 of the paper may be just small enough to enable it to be received between the two flanges 26 of plate 20.

Each of the clips 14 includes a holding unit or part 33 which desirably takes the form of an elongated internally and externally cylindrical tube, as shown, centered and mounted to turn about an axis 34 extending transversely of axis 29 and planes 28 of FIG. 4. This tube 33 of each of the clips 14 has along one of its sides a narrow slit 35, which may be of uniform width along the entire length of the tube or holding unit 33, and which is of a width to easily receive an end portion of abrasive sheet 13. More particularly, this slit deSirably has a width between about one thirty-second 'of an inch and three thirty-seconds of an inch, and preferably approximately one-sixteenth of an inch. Tube 33 may be formed of steel or other metal, and may have a wall thickness sufficiently great to render the tube rigid and of fixed dimension in all conditions of the device.

When sandpaper 13 is not in place on the tool, tube 33 may rest downwardly against, and exert downward force against, the upper horizontal surface 36 of portion 27 of plate 20. This condition of the apparatus is illustrated in FIG. 5, in which tube 33 engages surface 36 along a line of contact at 37 extending parallel to axis 34 and transversely of axis 29. Tube 33 may be held against surface 36 by a leaf spring 38, one end of which is rigidly secured to portion 27 of plate 20, as by two rivets 39 (FIG. 4). In extending from rivets 39 toward the nearest end of the tool, leaf spring 38 may first advance gradually upwardly at 40 (FIG. 5), and may then extend arcuately or cylindrically about the longitudinally central portion of tube 33 at 41, to terminate at an edge 42 of the leaf spring, extending parallel to axis 34. This portion 41 of the leaf spring which extends about the upper side of tube 33, and has an internal diameter corresponding closely to the external diameter of the tube, urges the tube downwardly against portion 27 of plate 20, and also confines the tube in a manner such that its only freedom for motion is rotatively about axis 34. The end portions of flanges 26 cooperate with leaf spring 38 in preventing axial movement of tube 33.

The tube 33 is turned -about axis 34 by a spring element 43 (FIG. 5), which has a torsion bar portion 44 extending axially within tube 33, along its longitudinal axis 34. At one of its ends, this portion 44 of spring 43 is turned radially outwardly at 45, through an aperture 46 in the side wall of tube 33, and then is turned through a short distance axially or generally axially at 47, at the outside of the tube, so that rotation of the spring 43 about axis 34 will correspondingly turn tube 33 about that axis. Torsion portion 44 projects outwardly beyond one end of tube 33, to a location 48 just outwardly of one of the anges 26 of plate 20, and is then turned to form an actuating spring arm 49 extending radially outwardly or transversely of axis 34. The end of this arm 49 is turned at 50 to form a hook portion (FIGS. 3 and 6), adapted to t over the upper edge of one of the flanges 26 to lock the arm in an active gripping condition. As will be apparent from the figures, spring 43 may be formed of a single piece of spring wire, deformed to the illustrated configuration and having the appropriate resilience to enable it to function in the manner brought out hereinbelow.

To now describe the operation of the discussed tool, assume that initially both of the clips 14 are in the condition of the clip illustrated in FIG. 5, with no sandpaper as yet applied to the tool. With the clips in this condition, the sheet of sandpaper 13 is located properly at the underside of plate 20 of the shoe 12, and one of its ends is turned upwardly about the ends of plate 20 and cushion 31, and is extended into slit 35 of tube 33, as indicated in FIG. 5. In this FIG. 5 condition of the parts, the various parts of the spring 43 assume the positions represented in FIGS. 5 and 6, and are not under tension of any type. After the paper has been inserted into slit 35 to the position of FIG. 5, arm 49 of the spring is swung in a clockwise direction from the FIG. 5 position to the FIG. 2 position, to correspondingly turn tube 33 to its FIG. 2 position. As the tube turns, about axis 34, it pulls the engaged end portion of sandpaper 13 leftwardly beneath tube 33, forcing the tube slightly upwardly against the resilience of its retaining leaf spring 3S, so that the sandpaper is thereafter clamped vertically between tube 33 and plate 20, under the influence of the spring force exerted by leaf spring 38. Arm 49 of spring 43 is locked in the FIG. 2 setting by positioning hook portion 50 of the spring 43 over the upper edge of flange 26 as seen in FIG. 3. In the condition of FIGS. 2 and 3, spring 43 is under substantial tension, being distorted substantially from its normal condition, but not far enough to reach its elastic limit, so that the spring force within element 43 constantly urges tube 33 in a clockwise direction tending to take up any looseness which may at any time develop in sandpaper sheet 13. More specifically, portion 44 of spring 43 functions as a torsion spring which is twisted about axis 34 in a direction tending to turn tube 33 in a clockwise direction beyond the FIG. 2 position, while the arm 49 of the spring is also distorted, to the slightly bowed condition of FIG. 2, to store in that arm additional yielding force tending to turn tube 33 in a clockwise direction. Together, the portions 44 and 49 attain a very effective take-up action, which produces also a reactive force urging hook 50 downwardly and preventing accidental dislocation of the hook from flange 26. After one of the clips 14 has been actuated to locked position as discussed, the second end of the sandpaper is locked in position by the other clip, so that the paper is very positively retained by the clips in a manner precluding any possibility of dislocation of the paper from the tool when motor 16 is energized and shoe 12 and its carried paper 13 commence oscillation on an engaged work piece. When it is desired to remove or replace the abrasive sheet 13, the two arms 49 of the clip springs 43 are manipulated to release their hook portions 56 from engagement with anges 26, and are swung to the FIG. 5 released positions in which the ends of the paper may be slipped out of slits 35 of tubes 33, and a replacement sheet of sandpaper may be applied to the tool in the same manner discussed above in connection with the first sheet.

I claim:

1. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a Work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a tubular holding unit adapted to retain said sheet and mounted to turn about an axis relative to said body structure in a direction tightening the sheet thereon, said tubular holding unit having a slit in its side wall and through which a portion of said sheet extends into the interior of said unit for retention thereby, and means for yieldingly urging said tubular holding unit rotatively about said axis in said direction to tighten the sheet.

2. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a holding unit adapted to retain said sheet and mounted to turn about an axis relative to said body structure in a direction tightening the sheet thereon, means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, and means forming a surface adjacent said holding unit and facing generally radially inwardly toward said axis at a location to pass the retaining sheet between said unit and said surface in a position of confinement and retention therebetween, said holding unit having a coacting peripheral surface located opposite and facing said first mentioned surface to confine and receive said sheet therebetween and facing generally radially outwardly away from said axis.

3. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a holding unit adapted to retain said sheet and mounted to turn about an axis relative to said body structure in a direction tightening the sheet thereon, means yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, means forming a surface adjacent said holding unit at a location to pass the retaining sheet between said unit and said surface, and means yieldingly urging said holdingunit and said surface relatively together to clamp said sheet therebetween.

4. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a holding unit adapted to retain said sheet and mounted to turn about an axis relative to said body structure in a direction tightening the sheet thereon, means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, means formng a surface adjacent said holding unit at a location to pass the retaining sheet between said unit and said surface, and means yieldingly urging said holding unit toward said surface to clamp said sheet thereagainst.

5. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a holding unit adapted to retain said sheet and mounted to turn about an axis relative to said body structure in a direction tightening the sheet thereon, means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, means forming a surface adjacent said holding unit at a location to pass the retaining sheet between said unit and said surface, and a leaf spring yieldingly urging said holding unit toward said surface to clamp said sheet thereagainst and shaped to coniine and guide said unit for said turning movement about said axis.

6. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a holding unit adapted to retain said sheet and mounted to turn about an axis relative to said body structure in a direction tightening the sheet thereon, means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, means forming a surface adjacent said holding unit at a location to pass the retaining sheet between said unit and said surface, said holding unit having a generally cylindrical outer surface, and a leaf spring yieldingly urging said holding unit toward said surface and having a generally arcuate portion receiving said outer surface of the holding unit in a relation conning and guiding said unit for said turning movement.

7. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a tubular holding unit adapted to retain said sheet and mounted to turn about an axis relative to said body structure in a direction tightening the sheet thereon, said tubular holding unit having a slit in its side wall extending along one side thereof and through which a portion of said sheet extends into the interior of said unit for retention thereby, means for yieldingly urging said tubular holding unit rotatively about said axis in said direction to tighten the sheet, means forming a surface adjacent said holding unit at a location to pass the retaining sheet between said unit and said surface, said holding unit having a generally cylindrical outer surface, and a leaf spring yieldingly urging said holding unit toward said surface and having a generally arcuate portion receiving said outer surface of the holding unit in a relation confining and guiding said unit for said turning movement.

S. An abrading tool comprising a body structure for removablyholding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet rnay be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a holding unit adapted to retain said sheet and mounted to t-urn about an axis relative to said lbody structure in a direction tightening the sheet thereon, a spring Aunit for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the unit, and means forming a flange on said body structure engageable with said spring unit to maintain it under tension for exerting yielding rotary force on said holding unit, and from which said spring unit is releasable to free said holding unit to turn in the opposite direction to release the abrasive sheet, said spring unit having an elongated actuating arm which swings to an active holding position at a first side of said flange, and which carries a hook shaped to extend over the liange from said lirst side thereof to its opposite side, while said arm remains at said lirst side, to thereby releasably retain the spring unit in said active position.

9. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a holding unit which is essentially tubular about an axis and is adapted to retain said sheet and mounted to turn about said axis relative to said body structure in a direction tightening the sheet thereon, and means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the unit and including a spring having a portion received within said essentially tubular holding unit.

10. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, an-d a clip for releasably retaining said sheet on said body structure, said clip including a holding unit which is essentially tubular about an axis and is adapted to retain said sheet and mounted to turn about said axis relative to said body structure in a direction tightening the sheet thereon, and means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the unit and including a spring having a torsion portion extending generally parallel to said axis within said essentially tubular holding unit and yieldingly twistable to exert yielding force on said holding unit.

11. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a Work piece, and a clip for releasably retaining said sheet on said body structure, said clip inclu-ding a holding unit which is essentialy tubular about an axis and is adapted to retain said sheet and mounted to turn about said axis relative to said body structure in a direction tightening the sheet thereon, and an elongated spring unit for yieldingly urging said holding unit rotatively about said axis in sai-d direction to tighten the sheet, said spring unit having a torsion portion extending essentially axially Within said essentially tubular holding unit and having an actuating arm portion extending essentially away from said axis at the outside of said holding unit and mounted to swing essentially about the axis between an active sheet holding position and a retracted released position.

12. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a hol-ding unit adapted to retain said sheet and mounted to turn about an axis relative to said body structure in a direction tightening the sheet thereon, an elongated spring unit for yieldingly urging said holding unit rotatively about said axis in a direction to tighten the holding unit, said spring unit having a torsion portion extending essentially axially within said holding unit and having an actuating arm portion extending essentially away from said axis and mounted to swing essentially about the axis between an active sheet holding position and a retracted released position, and means carried by said body structure for releasably locking said arm portion of the spring -unit in said active position.

13. A abrading tool as recited in claim 12, in which sa-id last mentioned means include a side flange carried by the body, said arm portion having an end turned to releasably lock over said ange to hold the arm portion in active position.

14. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said Sheet is to extend and by which the sheet may be held against a work piece, and a clip for releasably retaining said sheet on said body structure, said clip including a tubular holding unit adapted to retain said sheet and mounted to turn about an axis relative to said body structure in a direction tightening the sheet thereon, said tubular holding unit having a slit in its side wall extending along one side thereof and through which a portion of said sheet extends into the interior of said unit for retention thereby, an elongated spring unit for yieldingly urging said tubular holding unit rotatively about said axis in a direction to tighten the unit, said spring unit having a torsion portion extending essentially axially within said holding unit and having an actuating arm portion extending essentially away from said axis and mounted to swing essentially about the axis between an active sheet holding position and a retracted released position, means carried by said body structure for releasably locking said arm portion of the spring unit in said active position, means forming a surface adjacent said holding unit at a location to pass the retained sheet between said unit and said surface, and a leaf spring yieldingly urging said holding unit toward said surface to clamp said sheet thereagainst and shaped to confine and guide said unit for said turning movement about said axis.

1S. A clip for releasably securing an abrasive sheet to a tool body, comprising a holding unit for retaining said sheet and constructed to turn about an axis relative to said body in a direction tightening the sheet thereon, means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, and additional means yieldingly urging said holding unit transversely of said axis and toward an opposed surface to clamp said sheet thereagainst.

16. A clip for releasably securing an abrasive sheet to a tool body, comprising a holding unit for retaining said sheet and constructed to turn about an axis relative to said body in a direction tightening the sheet thereon, means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, and a leaf spring yieldingly urging said holding unit transversely of said axis and toward an opposed surface to clamp said sheet thereagainst and shaped to conne and guide said unit for said turning movement about said axis.

17. A clip for releasably securing an abrasive sheet to a tool body, comprising a holding unit for retaining said sheet, said unit being essentially tubular about an axis and constructed to turn about said axis relative to said body in a direction tightening the sheet thereon, and means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, said yielding means including a spring having a torsion portion received within said essentially tubular holding unit.

18. A clip for releasably securing an abrasive sheet to a tool body, comprising a holding unit for retaining said sheet, said unit being essentially tubular about an axis and constructed to turn about said axis relative to said body in a direction tightening the sheet thereon, and means for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, said yielding means including an elongated spring unit for yieldingly urging said holding unit rotatively about said axis in said direction to tighten the sheet, said spring unit having a torsion portion extending essentially axially within said essentially tubular holding unit and having an actuating arm portion extending essentially away from said axis at the outside of said holding unit and mounted to swing essentially about the axis between an active sheet holding position and a retracted released position.

19. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and

a `clip structure for releasably retaining said sheet on said body structure, said clip structure including a holding unit adapted to retain an end portion of said sheet and mounted for rotary take-up motion about an axis relative to said body structure in a predetermined take-up direction and acting upon such rotary motion to exert a tensional force on said sheet longitudinally of the sheet to tighten it on the body structure, and means for yieldingly urging said holding unit rotatively about said axis in said take-up direction to exert said tensional force on the sheet and maintain it in tightened condition, said rotary take-up motion of the holding unit in said tightened condition of the sheet being limited primarily by the tension of the sheet itself, and not by any positive stop shoulder, to thereby enable continuous maintenance of the sheet in tensioned condition and resultant automatic take-up by said yielding means of any looseness which may develop in use of the tool.

20. An abrading tool as recited in claim 19, in which said yielding means include a spring for urging the holding unit rotatively in said take-up direction, and which is releasable to free the unit for rotary motion in the opposite direction to release the abrasive sheet.

21. An abrading tool as recited in claim 19, in which said yielding means include a resilient spring arm extending essentially outwardly away from said axis and adapted to swing essentially vabout said axis, and means releasably engabeable by said arm to lock it in a force applying position.

22. An abrading tool comprising a body structure for removably holding a sheet -of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, and a yholding unit adapted to releasably retain an end portion of said sheet and yieldingly urged in a predetermined take-up direction relative to said body structure and acting upon take-up motion in said direction to` exert a tensional force on said sheet longitudinally of the sheet to maintain it in tightened condition on the body structure,

said take-up motion, in said tightened condition of the sheet, being limited primarily by the tension of the sheet itself, and not by an positive stop shoulder, to thereby enable continuous maintenance of the sheet in tensioned condition and resultant automatic take-up by said yielding means of any looseness which may develop in use of the tool.

23. A clip for releasably securing an abrasive sheet to a tool body, comprising a holding unit for retaining said sheet and constructed for rotary motion about an axis relative to said body in a predetermined take-up direction and acting upon such rotary motion to exert a tensional force on the sheet longitudinally thereof to tighten it on the body, and means for yieldingly urging said holding unit rotatively about said axis in said take-up direction to exert said tensional force on the sheet and maintain it in tightened condition, said rotary take-up motion of the holding unit, in said tightened condition, being limited primarily by the tension of the sheet itself, and not by any positive stop shoulder, to thereby enable continuous maintenance of the sheet in tensioned condition and resultant automatic take-up by said yielding means of any looseness which may develop in use of the tool.

24. An abrading tool comprising a body structure for removably holding a sheet of abrasive material and having a backing portion along which said sheet is to extend and by which the sheet may be held against a work piece, an essentially tubular holding unit for retaining an end portion of said sheet and mounted for rotary motion about an axis and having a slit through which said sheet may project into the interior of the essentially tubular unit, and means yieldingly urging said essentially tubular unit rotatively about said axis.

References Cited UNITED STATES PATENTS 1,947,054 2/1934 McReynolds 51-384 X 2,435,335 2/1948 Andrews 51-361 2,683,337 7/1954 Scace 51--384 2,893,174 7/1959 Jepson 51-170 3,267,622 8/1966 Frostad 51-384 ROBERT C. RIORDON, Primary Examiner. D. G. KELLY, Assistant Examiner. 

4. AN ABRADING TOOL COMPRISING A BODY STRUCTURE FOR REMOVABLY HOLDING A SHEET OF ABRASIVE MATERIAL AND HAVING A BACKING PORTION ALONG WHICH SAID SHEET IS TO EXTEND AND BY WHICH THE SHEET MAY BE HELD AGAINST A WORK PIECE, AND A CLIP FOR RELEASABLY RETAINING SAID SHEET ON SAID BODY STRUCTURE, SAID CLIP INCLUDING A HOLDING UNIT ADAPTED TO RETAIN SAID SHEET AND MOUNTED TO TURN ABOUT AN AXIS RELATIVE TO SAID BODY STRUCTURE IN A DIRECTION TIGHTENING THE SHEET THEREON, MEANS FOR YIELDABLY URGING SAID HOLDING UNIT ROTATIVELY ABOUT SAID AXIS IN SAID DIRECTION TO TIGHTEN THE SHEET, MEANS FORMING A SURFACE ADJACENT SAID HOLDING UNIT AT A LOCATION TO PASS THE RETAINING SHEET BETWEEN SAID UNIT AND SAID SURFACE, AND MEANS YIELDINGLY URGING SAID HOLDING UNIT TOWARD SAID SURFACE TO CLAMP SAID SHEET THEREAGAINST. 